Method and apparatus for draining a work piece during finishing

ABSTRACT

A method of processing a work piece having an enclosure. The method comprises inserting a siphon into the enclosure, submerging the work piece in an immersion tank, removing the work piece from the tank, and draining liquid from the enclosure through the siphon. Inserting can include positioning at least a portion of a short leg of the siphon in the enclosure of the work piece. Preferably, draining includes directing liquid back into the immersion tank. After draining, the work piece can be moved to a second workstation and/or the siphon can be withdrawn from the enclosure. The method can be performed using a finishing system comprising a primary carrier, a work piece suspended from the primary carrier and defining an enclosure, and a siphon positioned in the enclosure. Preferably, the work piece is suspended above an immersion tank. The siphon can be positioned to direct fluid toward the immersion tank.

CROSS-REFERENCE TO RELATED APPLICATIONS

Priority is hereby claimed to U.S. provisional patent application No. 62/094,784 filed on Dec. 19, 2014, the entirely of which is incorporated herein by reference.

BACKGROUND

The present invention relates to finishing systems and processes for manufactured parts, and more particularly to carriers for transporting manufactured parts through a finishing process and methods relating to the same. For example, a finishing process can include a painting or an electroplating process whereby manufactured parts are immersed in a dip tank full of fluids. The shape of complex parts (e.g., containers and automotive parts) can introduce difficulty in ensuring full drainage of fluid from the parts after removal from a dip tank.

To facilitate drainage of dip tank fluid from a part, parts are often provided with drain holes formed in the part. These drain holes are typically provided solely to facilitate drainage of fluids from the part, and are often otherwise undesirable. Without drain holes, complex and costly machines must be utilized to ensure good coverage of and drainage of fluid from complex parts. Without such measures, a significant amount of liquid may be lost from the dip tank during the process, which increases processing time and cost due to stoppages, re-filling, and treatment or disposal, and may also negatively affect downstream portions of the finishing process.

SUMMARY

The present invention provides a method and apparatus of processing a work piece having an enclosure through a workstation having an immersion tank with liquid. The method comprises inserting (e.g., attaching) a siphon at least partially into the enclosure of the work piece, submerging at least a portion of the work piece (e.g., the entire work piece) in the immersion tank to thereby cause the liquid in the immersion tank to at least partially fill the siphon and the enclosure in the work piece, removing (e.g., lifting) the work piece from the immersion tank, and draining liquid from the enclosure through the siphon. In one embodiment, the siphon includes a short leg and a long leg, and inserting includes positioning at least a portion of the short leg in the enclosure of the work piece. Preferably, draining includes directing liquid from the siphon back into the immersion tank.

If desired, after draining, the method can include moving the work piece to a second workstation. The second workstation can include any additional manufacturing process, such as dipping the work piece into a second immersion tank with a second liquid. After draining, the siphon can be withdrawn from the enclosure.

The method can be performed using a finishing system comprising a primary carrier, a work piece suspended from the primary carrier and defining an enclosure, and a siphon having an inlet end positioned in the enclosure. When used to perform the above-referenced method, the finishing system further includes a workstation having an immersion tank, and the work piece is suspended above the immersion tank. Preferably, the siphon is positioned to direct fluid from the enclosure toward the immersion tank. An attachment means can be provided to secure the siphon to the work piece.

The finishing system can also include a second workstation and a conveyor positioned to move the work piece to the second workstation. As noted above in connection with the method, the second workstation can include a second workstation having a second immersion tank. In the event that the work piece defines two enclosures, two siphons can be provided, one for each enclosure.

Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a carrier assembly for moving a work piece between two workstations and embodying the present invention.

FIG. 2 is a side view of the carrier assembly of FIG. 1 at a single workstation.

FIG. 3 is a side view of the carrier assembly of FIG. 2 with a work piece lowered into an immersion tank.

FIG. 4 is a side view of the carrier assembly of FIG. 2 with the work piece removed from and held above the immersion tank, so that liquid flows from the work piece through a drainage siphon back into the immersion tank.

FIG. 5 is a side view of a different work piece after removal from an immersion tank.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.

A finishing system is illustrated in FIGS. 1-4. The finishing system includes a conveyor 22, a carrier assembly 10, and a plurality of workstations 18. The carrier assembly includes a primary carrier or load bar 14 configured to be transported between the workstations 18 (FIG. 1) by the conveyor 22 as part of a conveyor system. Each workstation 18 is designed to perform a different manufacturing process, such as dipping, painting, drying, drilling, or attaching another component. In the carrier assembly of FIG. 1, both of the workstations involve dipping.

The load bar 14 can be a rigid structure that is coupled to the conveyor 22 for traveling along the conveyor 22 between work stations 18. A work piece 26 is supported below the conveyor 22 by the load bar 14. The work piece 26 is coupled to lower ends of one or more hangers or brackets 30, and the load bar 14 is coupled to upper ends of the hangers 30 such that the work piece 26 is configured to hang from the load bar 14. The hangers 30 can be pivotally coupled to the load bar 14 and the work piece 26, and can also be rigid members, such as beams, rods, poles, shafts or bars, in some constructions. However, in other constructions, the hangers 30 can be flexible members such as chains, cables and ropes, etc. But the work piece 26 may be supported by the conveyor 22 in any manner with or without any additional structure via any convenient connection points on the load bar 14, and the work piece 26. In alternate constructions, additional structure, such as a skid may be coupled to the hangers 30 and connected to the load bar 14 by any connection points to carry the work piece 26, and the work piece 26 can be directly or indirectly fastened to the skid. Regardless of whether the carrier assembly 10 includes a skid or additional structure, the work piece 26 is configured to move along with the load bar 14 via the conveyor 22.

Though the conveyor system shown in FIG. 1-3 illustrates only a single carrier assembly 10, the conveyor system may include any number of carrier assemblies 10. The conveyor 22 can be part of any overhead conveyor system between the plurality of work stations 18. Further, the conveyor system can be adapted accordingly so it moves in any suitable direction. In particular, the conveyor 22 transports the plurality of carrier assemblies 10 between the plurality of work stations 18. The work stations 18 may include finishing stations, such as an electroplating immersion tank 32 for submerging the work piece 26 into an electro-coating liquid, as illustrated in FIGS. 1-3. In order to coat the work piece 26 at the finishing station, the work piece 26 is at least partially submerged in the immersion tank 32 and then removed. Depending upon the type of coating, the liquid in the tanks and the work piece 26 to be coated may be oppositely electrically charged to promote adhesion. However, the work stations 18 are not limited to such an example, and can include one or more of electro-coating, autodeposition coating, powder coating, liquid spray painting, cleaning, chemical etching, pre-treatment, and heat treating operations. Additionally, the work stations 18 can also include other types of equipment, such as an oven or drying station, a paint spray station, a cleaning station and the like.

The work piece 26 is illustrated as a box or case forming an enclosure, but may be of almost any shape, and particularly a shape that forms an enclosure 34 that retains liquid when the work piece 26 is removed from the immersion tank 32. Although some conveyor systems are equipped with complex manipulation capability, the conveyor 22 illustrated is only equipped to lower and raise the work piece 26 without tilting and rotation capability. Thus, the illustrated work piece 26 orientation required for good coverage leads to unavoidable liquid retention upon removal from the immersion tank 32. In other constructions, the conveyor 22 and/or the carrier assembly 10 may enable tilting of the work piece 26 to enhance liquid coverage in the immersion tank 32, but the tilting capability is often not sufficient to empty the liquid from the enclosure 34 in the work piece 26. Thus, a drainage siphon 38 is further provided for removing the liquid that is retained by the enclosure of the work piece 26 after the work piece 26 is removed from the immersion tank 32.

The drainage siphon 38 is illustrated as a tube that includes a long leg 42 and a short leg 46 that are in fluid communication. The short leg 46 is positioned inside the enclosure 34 adjacent a bottom of the enclosure 34 and generally near a location where the liquid tends to be retained. The long leg 42 is positioned exterior to the enclosure 34 and the work piece 26, substantially below a bottom side 50 of the work piece 26, so that an outlet 54 defined by a distal end of the long leg 42 is lower than an inlet 58 defined by a distal end of the short leg 46. Due to the gravitational potential energy difference between the liquid in the enclosure 34 and the outlet 54, the liquid will be siphoned from the enclosure 34 of the work piece 26 by the inlet 58 of the drainage siphon 38. The liquid is then discharged by the outlet 54 of the drainage siphon 38, thereby removing most of the liquid retained by the enclosure 34 of the work piece 26. The long leg 46 is arranged to direct the liquid through the outlet 54 of the drainage siphon 38 back into the immersion tank 32. However, in other constructions the liquid may be discharged to another container or location.

When the work piece 26 and drainage siphon 38 are initially submerged in the liquid in the immersion tank 32, liquid enters the outlet 54 of the drainage siphon 38 and the inlet 58 of the drainage siphon 38 as liquid enters the enclosure 34. This entry of fluid into both ends of the siphon can result in the formation of an air bubble near a pipe bend 62 between the long leg 42 and the short leg 46.

Upon lifting the work piece from the tank, the siphon will cause liquid in the work piece to flow into the inlet 58 and flow out of the outlet 54. Specifically, the weight of the liquid in the long leg 42 is greater than the weight of the liquid in the short leg 46, and thus liquid will flow through the long leg 42 towards the outlet 54. The liquid from the enclosure 34 initially pulls any air bubble out through outlet 54, after which the liquid continues to flow from the enclosure 34 to the immersion tank 32 through the drainage siphon 38. Due to the pressure decrease from the inlet 58 to the top of the drainage siphon 38, which is below atmospheric pressure, the liquid is lifted through the short leg 46, from the enclosure 34 up to the pipe bend 62 where the liquid can then fall, due to gravity, through the long leg 42, and be discharged out the outlet 54. The liquid continues to be removed from the enclosure 34 by the drainage siphon 38 until most liquid is removed from the enclosure 34, or the liquid level in the immersion tank 32 is at the same height as the liquid level in the enclosure 34.

The drainage siphon 38 is illustrated as a rigid tube having a rigid 180-degree pipe bend 62 fluidly connecting the short leg 46 and the long leg 42 to orient the long leg 42 downward so that the outlet 54 is below the inlet 46 of the drainage siphon 38. In other constructions the drainage siphon 38 may be a flexible conduit configured to have the outlet 54 beneath the inlet 58. In the illustrated construction a length L1 of the long leg 42 is approximately twice as long as a length L2 of the short leg 46. In other constructions the length L1 of the long leg 42 may instead be three times longer than the length L2 of the short leg 46, or any other amount longer. The length L1 of the long leg 42 is preferably long enough that the outlet 54 is positioned below a bottom of the enclosure 34 so that all water stored in the enclosure is removed. The length L2 of the short leg 46 is long enough that it extends to the bottom of the enclosure 34. Alternatively, in other constructions, the long leg 42 of the drainage siphon 38 may be telescopic or collapsible so that the length L1 of the long leg 42 can be variably increased or decreased as necessary. The short leg 46 may also be independently telescopic, or expandable and collapsible. Further, the long leg 42 and the short leg 46 may also both be independently telescopic. If the drainage siphon 38 is a flexible conduit it may also be expandable and configurable to properly direct liquid flow.

In the illustrated construction, the drainage siphon 38 is coupled to an inside and/or outside surface of the work piece 26 by an attachment means in the form of a bracket 66 or fastener. Additionally, brazing, welding, permanent or removable fasteners, and the like may be used in combination with or without the bracket 66 and/or fastener to couple the drainage siphon 38 to the work piece 26. Examples of fasteners that can be used (with or without a bracket) to attach the drainage siphon 38 to the work piece 26 include without limitation a clip, clamp, elastic element, permanent magnet, electromagnet, cable tie, clasp, hook, cord, adhesive, hook-and-loop strips or any other suitable component, or combination of components. The drainage siphon 38 can be permanently or releasably attached to the work piece 26 by a bracket 66 and/or a fastener as disclosed herein. Alternatively, the drainage siphon 38 can hang from the work piece without any additional attachment means. The drainage siphon 38 may also be frictionally fit to an integral component of the work piece 26, or alternatively, the drainage siphon 38 may be integrally formed as part of the work piece 26. However, in further constructions, the drainage siphon 38 may not be coupled to the work piece 26 at all, and may instead hand from the work piece or be coupled to the carrier assembly 10, or integrated therewith, such that the drainage siphon 38 is not supported by the work piece 26. In such constructions, the drainage siphon 38 may be maintained out of contact with the surfaces of the work piece 26, thus preventing any interference with the surface treatment that coupling the drainage siphon 38 directly to the work piece 26 may produce during submersion in the immersion tank 32. In some constructions where the drainage siphon 38 is coupled to the work piece 26, the point of contact may be a preselected portion of the work piece 26 not designated or required to receive the coating or other finishing. The drainage siphon 38 may be attached to the work piece 26 or the carrier assembly 10 prior to the work piece 26 being loaded onto the conveyor system. Alternatively, the drainage siphon 38 may be attached to the work piece 26 or carrier assembly 10 at any point during the process.

A process of conveying one or more work pieces 26 through a finishing process can include the following steps. First, the work piece 26 is connected to the conveyor 22 by the hangers 30. If not pre-attached, the drainage siphon 38 is provided in communication with the enclosure 34 of the work piece 26. The conveyor 22 is operated to transport the work piece 26 to a work station 18. The conveyor 22 may transport the work piece 26 directly into the work station 18 along the primary direction of travel A, or may first transport the work piece 26 to a position above the work station 18 (e.g., in the case of an immersion tank holding an electrocoating liquid). A vertical drive may lower the carrier assembly 10 from the conveyor 22 so that the work piece 26 is lowered into the work station 18. The vertical drive can include any suitable system for producing the required vertical travel (e.g., motor, or hydraulic cylinders). Alternately, the conveyor 22 may follow a path that descends to allow the work piece 26 to descend into the work station 18. The work piece 26 can be lowered while traveling along the conveyor 22 or after stopping at a position along the conveyor 22 corresponding to the desired work station 18. In the case where the work station 18 includes an immersion tank 32 containing an electro-coating liquid, the work piece 26 and the drainage siphon 38 are lowered into the immersion tank 32 so that at least a portion of the work piece 26 is submerged within the immersion tank 32 (FIG. 2). While the work piece 26 is submerged, the liquid coats the work piece 26 and also flows into the enclosure 34 of the work piece 26. Once the work piece 26 is coated thoroughly by the liquid, which may include one or more minor oscillations, the work piece 26 and the drainage siphon 38 are removed from the immersion tank 32 (FIG. 3). The liquid then flows from the enclosure 34 of the work piece 26 back into the immersion tank 32 via the drainage siphon 38. Once most of the liquid is removed from the enclosure 34 of the work piece 26, the work piece 26 is transported via the conveyor 22 to another work station 18 or to an unloading area of the conveyor system. Once the work piece 26 is unloaded, the drainage siphon 38 may be removed and reused with another work piece 26 on the same or different carrier assembly 10 in the conveyor system.

The system and method described herein are applicable for any number of work stations 18. In some constructions, the carrier assembly 10 may include and support more than one work piece 26 each having a drainage siphon 38 for removing liquid from an enclosure. Additionally, referring to FIG. 5, more than one drainage siphon 70 may be used in conjunction with the same work piece 72 to accommodate a plurality of fluidly separate enclosures 74, or to increase the speed at which liquid is removed from the work piece 72. 

1. A method of processing a work piece having an enclosure through a workstation having an immersion tank with liquid, the method comprising: inserting a siphon at least partially into the enclosure of the work piece; submerging at least a portion of the work piece in the immersion tank to thereby cause the liquid in the immersion tank to at least partially fill the siphon and the enclosure in the work piece; removing the work piece from the immersion tank; and draining liquid from the enclosure through the siphon.
 2. A method as claimed in claim 1, wherein inserting includes attaching the siphon to the work piece.
 3. A method as claimed in claim 1, wherein the siphon includes a short leg and a long leg, and wherein inserting includes positioning at least a portion of the short leg in the enclosure of the work piece.
 4. A method as claimed in claim 1, wherein submerging includes submerging the entire work piece in the liquid.
 5. A method as claimed in claim 1, wherein removing includes lifting the work piece out of the immersion tank.
 6. A method as claimed in claim 1, wherein draining includes directing liquid from the siphon back into the immersion tank.
 7. A method as claimed in claim 1, further comprising, between inserting and submerging, positioning the work piece above the immersion tank.
 8. A method as claimed in claim 1, further comprising, after draining, moving the work piece to a second workstation.
 9. A method as claimed in claim 8, wherein the second workstation includes a second immersion tank with a second liquid.
 10. A method as claimed in claim 1, further comprising, after draining, withdrawing the siphon from the enclosure.
 11. A method as claimed in claim 1, further comprising removably attaching the siphon to the work piece by either or both of a bracket and a fastener.
 12. A finishing system comprising: a primary carrier; a work piece suspended from the primary carrier, the work piece defining an enclosure; and a siphon having an inlet end positioned in the enclosure.
 13. A finishing system as claimed in claim 12, further comprising a workstation having an immersion tank, the work piece being suspended above the immersion tank.
 14. A finishing system as claimed in claim 13, wherein the siphon is positioned to direct fluid from the enclosure toward the immersion tank.
 15. A finishing system as claimed in claim 13, further comprising: a second workstation; and a conveyor positioned to move the work piece to the second workstation.
 16. A finishing system as claimed in claim 15, wherein the second workstation comprises a second immersion tank.
 17. A finishing system as claimed in claim 12, wherein the work piece defines two enclosures, and wherein the siphon comprises two siphons, each siphon having an inlet end positioned in one of the two enclosures.
 18. A finishing system as claimed in claim 12, further comprising an attachment means for securing the siphon to the work piece.
 19. A finishing system as claimed in claim 12, further comprising either or both of a bracket and a fastener positioned to couple the work piece to the siphon.
 20. The finishing system as claimed in claim 19, wherein the bracket or fastener is releasably coupled to the work piece. 